OBJECTIVES: In 'exploratory mode', to examine associations between occupational exposure to 49 prevalent agents and breast cancer risk. METHODS: In a French population-based case-control study on breast cancer (2005-2007), lifetime occupational histories of 1230 incident cases and 1315 controls were collected. An industrial hygienist coded each job held by a participant. Job codes were subsequently linked to the Canadian job-exposure matrix, and exposure level estimates for numerous agents were generated. Multivariable unconditional logistic regression was used to estimate associations between occupational exposure to 49 prevalent agents and breast cancer risk, adjusting for established breast cancer risk factors and selected sociodemographic covariates. RESULTS: Increased ORs, ranging between 1.33 and 2.39, were observed for women in the highest tertile of cumulative exposure versus unexposed for the following 12 agents: sodium carbonate, synthetic fibres, wool fibres, silk fibres, organic dyes and pigments, plastic dusts, plastics pyrolysis fumes, ozone, nitrogen oxides, anaesthetic gases, aliphatic ketones and mononuclear aromatic hydrocarbons. When stratified by menopausal status, the ORs for many of these agents were stronger among premenopausal versus postmenopausal women. CONCLUSIONS: These findings suggest the possible role of some occupational agents in the aetiology of breast cancer. Further studies, based on large sample sizes and high-quality exposure assessment, are needed to confirm our findings.